1. Field of Invention
The present invention relates to a transflective liquid crystal device having a reflection display region and a transmission display region in one pixel. The invention also relates to electronic apparatuses including the same.
2. Description of Related Art
Related art liquid crystal devices that are capable of displaying images in both a transmission mode and a reflection mode are referred to as transflective liquid crystal devices, and can be used in many applications.
In such a transflective liquid crystal device, as shown in FIG. 21, an active matrix-type transflective liquid crystal device includes a TFT array substrate 10 (first transparent substrate) having a transparent pixel electrode 9a (first transparent electrode) and a pixel-switching TFT (Thin Film Transistor) 30 formed on the surface, a counter substrate 20 (second transparent substrate) having a counter electrode 21 (second transparent electrode) and a color filter 24, and a liquid crystal layer 50 held between the substrates 10 and 20. The substrate gap between the TFT array substrate 10 and the counter substrate 20 is defined by dispersing gap material 5 having a predetermined particle size on the surface of one of the substrates, and then sealing the TFT array substrate 10 and the counter substrate 20 by sealing material (not shown).
In such a liquid crystal device structured as above, the TFT array substrate 10 includes a light reflecting film 8a having a reflection display region 100b formed in a pixel 100 in which a pixel electrode 9a faces the counter electrode 21, a transmission display region 100c formed in the remaining region (light transmitting window 8d) where the light reflecting film 8a is not formed.
Therefore, with regard to the light emitted from a backlight apparatus (not shown) disposed on the back side of the TFT array substrate 10, the light incident into the transmission display region 100c, as indicated by arrow LB, is incident from the TFT array substrate 10 into the liquid crystal layer 50, and is light-modulated in the liquid crystal layer 50, and then is emitted from the counter substrate 20 as a transmission display light to display images (transmission mode).
Further, with regard to the external light incident from the counter substrate 20, the light incident into the reflection display region 100b, as indicated by arrow LA, passes through the liquid crystal layer 50, reaches the light reflecting film 8a, is reflected from the light reflecting film 8a, passes through the liquid crystal layer 50 again, and then is emitted from the counter substrate 20 as a reflecting display light to display images (reflection mode).
When performing the light modulation, if a twist angle of a liquid crystal is set to be small, the changes of the polarization state is shown as a function of multiplying the difference of an index of refraction Δn by the layer thickness “d” of the liquid crystal layer 50 (retardation (Δn·d)), and therefore, if the value is enhanced or optimized, a visibility of display becomes better.
However, in the transflective liquid crystal device, since the reflection display light passes through the liquid crystal layer 50 twice, while the transmission display light is emitted by passing through the liquid crystal layer 50 once, it is difficult to optimize the retardation (Δn·d) in both of the transmission display light and the reflection display light. Therefore, if the layer thickness “d” of the liquid crystal layer 50 is determined such that the display visibility in the reflection mode is enhanced, the display in the transmission mode is sacrificed. Or if the layer thickness “d” of the liquid crystal layer 50 is determined such that the display visibility in the transmission mode is enhanced, the display in the reflection mode is sacrificed.
Therefore, with regard to the TFT array substrate 10, a thick layer-thickness adjusting layer can be formed below the light reflecting layer 8a defining the reflection display region 100b, and the layer thickness “d” of the liquid crystal layer 50 in the reflection display region 100b be made thinner than the layer thickness “d” of the liquid crystal layer 50 in the transmission display region 100c. 
Such a related art method is disclosed in Japanese Unexamined Patent Application Publication No. 61-173221.